IN PRINCIPLE, Colombia’s government and the FARC leftist army both think it would be a good idea to shoot less at one another while they negotiate an end to their 50-year war. In practice, that is difficult. Violence has flared since April, when the FARC attacked an army patrol, killing 11 soldiers. The attack breached a unilateral ceasefire that the FARC declared in December. The government responded by resuming bombing raids on the guerrillas.

The situation has since deteriorated. An attack on a FARC camp in south-west Colombia on May 21st killed 27 guerrillas, including a former member of the negotiating team, and prompted the FARC formally to end its ceasefire. By May 26th another 15 rebels and two civilians had been killed in several skirmishes with the army.

The escalation has angered ordinary Colombians, who are impatient with the slow pace of the peace talks, which started in November 2012. It has hardened their hostility to the guerrillas. That will make it more difficult for Colombia’s president, Juan Manuel Santos, to win political backing for an eventual peace settlement. But it has not disrupted the peace process itself.

The talks resumed in Havana on May 25th. The government strengthened its team by adding the foreign minister, María Ángela Holguín, and Gonzalo Restrepo, a former chief executive of the Éxito Group, a retailer. His role may be to reassure the FARC that business will support a deal.

One reason for the talks’ resilience is that both sides are used to negotiating during bouts of violence, which did not end even during the quietest periods. Military action by the FARC fell by 85% during its ceasefire and civilian deaths fell by 73%, according to the Conflict Analysis Resource Centre (CERAC), a think-tank in Bogotá. Even so, CERAC recorded 21 attacks by the FARC (and suspects it was responsible for another 75). Mr Santos has staked his reputation on concluding a peace agreement (by the end of this year, he hopes). For the FARC, the alternative to peace is further pounding by the armed forces; it no longer hopes for victory.

The presence of Ms Holguín in Havana is necessary because the talks are focusing on the knottiest problem: “transitional justice” for combatants on both sides who may have committed war crimes. The FARC’s negotiators have yet to accept the principle that such crimes must be punished, even with milder sentences than would normally be imposed. Colombia’s citizens will not accept too much leniency. Nor will the International Criminal Court, as Ms Holguín is joining the discussions to point out. The prospects for peace may depend on whether the FARC’s leaders fear jail more than Colombia’s guns.